It's not a Daimler Conquest roadster proposal, but you are close...
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Perhaps it was a proposal for a Lanchester roadster (2½ litre 14 h.p.?) which wasn't proceeded with so we can't find anything about it.
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Spot on Allan L, the Lanchester 14 hp proposal was the answer I was looking for, for this sadly dormant Roadster proposal. Another point to you.